doc: notes: remove stripspace discussion from other options

doc: notes: remove stripspace discussion from other options

Cleaning up whitespace in metadata is typical porcelain behavior and
this default does not need to be pointed out.[1]  Only speak up when
the default `--stripspace` is not used.

Also remove all misleading mentions of comment lines in the process;
see the previous commit.

Also remove the period that trails the parenthetical here.

† 1: See `-F` in git-commit(1) which has nothing to say about whitespace
    cleanup.  The cleanup discussion is on `--cleanup`.

Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>